Or you could do a hash of arrays (perldsc) and use List::Util to generate the required results:

use strict;
use warnings;
use List::Util qw{sum min max};

my %data;
while (<DATA>) {
    chomp;
    my ($id, $value) = split /,/;
    push @{ $data{$id} }, $value; # store values as HoA
}

for my $id (sort keys %data) {
    print "$id:  " . summarise($data{$id});
}

sub summarise{
    my $arr = shift;
    return "max=" . max( @$arr ) 
        . " min=" . min( @$arr ) 
            . " sum=" . sum( @$arr ) 
                . " mean=" . ( sum( @$arr )/scalar@$arr ) 
                    . "\n";
}
__DATA__
A,10
A,11
A,12
A,13
B,15
B,16
C,17
D,18

[download]

Gives:

A:  max=13 min=10 sum=46 mean=11.5
B:  max=16 min=15 sum=31 mean=15.5
C:  max=17 min=17 sum=17 mean=17
D:  max=18 min=18 sum=18 mean=18

[download]

NB: Code pretty much exactly the same as toolic's post... Just wanted to show TIMTOWTDI!

Just a something something...

In reply to Re^2: get the average of hash values? by BioLion
in thread get the average of hash values? by luckysing

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